In the semiconductor production industry, various processing steps are used to fabricate integrated circuits on a semiconductor wafer. These steps include the deposition of layers of different materials including metallization layers, passivation layers and insulation layers on the wafer substrate, as well as photoresist stripping and sidewall passivation polymer layer removal. In modern memory devices, for example, multiple layers of metal conductors are required for providing a multi-layer metal interconnection structure in defining a circuit on the wafer. Chemical vapor deposition (CVD) processes are widely used to form layers of materials on a semiconductor wafer.
CVD processes include thermal deposition processes, in which a gas is reacted with the heated surface of a semiconductor wafer substrate, as well as plasma-enhanced CVD processes, in which a gas is subjected to electromagnetic energy in order to transform the gas into a more reactive plasma. Forming a plasma can lower the temperature required to deposit a layer on the wafer substrate, to increase the rate of layer deposition, or both. However, in plasma process chambers used to carry out these various CVD processes, materials such as polymers are coated onto the chamber walls and other interior chamber components and surfaces during the processes. These polymer coatings frequently generate particles which inadvertently become dislodged from the surfaces and contaminate the wafers.
In semiconductor production, the quality of the integrated circuits on the semiconductor wafer is directly correlated with the purity of the fabricating processes, which in turn depends upon the cleanliness of the manufacturing environment. Furthermore, technological advances in recent years in the increasing miniaturization of semiconductor circuits necessitate correspondingly stringent control of impurities and contaminants in the plasma process chamber. When the circuits on a wafer are submicron in size, the smallest quantity of contaminants can significantly reduce the yield of the wafers. For instance, the presence of particles during deposition or etching of thin films can cause voids, dislocations, or short-circuits which adversely affect performance and reliability of the devices constructed with the circuits.
Particle and film contamination has been significantly reduced in the semiconductor industry by improving the quality of clean rooms, by using automated equipment designed to handle semiconductor substrates, and by improving techniques used to clean the substrate surfaces. However, as deposit of material on the interior surfaces of the processing chamber remains a problem, various techniques for in-situ cleaning of process chambers have been developed in recent years. Cleaning gases such as nitrogen trifluoride, chlorine trifluoride, hexafluoroethane, sulfur hexafluoride and carbon tetrafluoride and mixtures thereof have been used in various cleaning applications. These gases are introduced into a process chamber at a predetermined temperature and pressure for a desirable length of time to clean the surfaces inside a process chamber. However, these cleaning techniques are not always effective in cleaning or dislodging all the film and particle contaminants coated on the chamber walls and interior chamber components. The smallest quantity of contaminants remaining in the chamber after such cleaning processes can cause significant problems in subsequent manufacturing cycles.
A typical conventional HDP deposition chamber manufactured by the Applied Materials Corp. of Santa Clara, Calif. is generally indicated by reference numeral 10 in FIG. 1. The HDP chamber 10 includes a base 12 having a chamber interior 14. A lid 13 hingedly attached to the base 12 selectively closes the chamber interior 14. An electrostatic chuck 18 inside the chamber interior 14 supports a cathode 20 on which a wafer substrated (not illustrated) is placed during the HDP deposition process. A typically ceramic cathode collar 22 shields the cathode 20 from damage by RF energy during the process.
As illustrated in FIG. 2, the cathode collar 22 typically includes an annular body 24, having an outwardly-extending rim 26 and an upwardly-extending flange 28. During the plasma deposition process, high-density deposition plasma forms material residues 27 on the cathode collar 22. These residues 27 must be removed from the cathode collar 22 during periodic maintenance of the HDP chamber 10 in order to prevent particle contamination of wafers subsequently processed in the chamber interior 14. Effective removal of the residues 27 from the cathode collar 22 requires that the cathode collar 22 be removed from the HDP chamber 10, cleaned and then replaced in the HDP chamber 10 during each periodic maintenance.
Conventional techniques for removing the cathode collar 22 from the HDP chamber 10 include grasping the cathode collar 22 with the fingers and manually lifting the collar 22 from the chamber 10. However, since the interior chamber walls 16 and the collar 22 are typically maintained at a temperature of about 70 degrees C., these elements present uncomfortably hot surfaces to the fingers and hands of personnel lifting the collar 22 from the chamber 10. Furthermore, the cathode collar 22 must typically be grasped at the body edge 25, which presents an inadequate height of just 2 mm to the fingers of the personnel while grasping and lifting the collar 22 from the chamber 10. Makeshift tools (not illustrated) not designed for the purpose have also been used in attempts to remove the collar 22. These tools usually apply excessive pressure to one or a small number of points on the collar 22 in the lifting process, and the excessive pressure tends to crack or damage the ceramic collar 22.
Accordingly, an object of the present invention is to provide a clamp for quickly, easily and safely removing a cathode collar from a HDP deposition chamber and replacing the collar in the chamber for cleaning, replacement or maintenance purposes.
Another object of the present invention is to provide a collar-removing clamp which is simple in construction and operation.
Still another object of the present invention is to provide a collar-removing clamp which saves time during preventative maintenance of an HDP deposition chamber.
Another object of the present invention is to provide a collar-removing clamp which is effective in removing a cathode collar from an HDP deposition chamber, which clamp is characterized by low risk of damaging the collar.
Yet another object of the present invention is to provide a collar-removing clamp which applies substantially equal pressure to opposite sides of a cathode collar during the removal of the collar from an HDP deposition chamber.
Another object of the present invention is to provide a collar-removing clamp which applies pressure to a relatively large area on a cathode collar to prevent excessive pressure application to a small area or areas on the collar and prevent damage to the collar.
A still further object of the present invention is to provide a collar-removing clamp which prevents cracking or damage to a cathode collar by preventing application of excessive pressure to a particular area or areas on the collar as the collar is removed from an HDP deposition chamber.